What Color Is Diesel Fuel? Here's What It Should Look Like

During a typical trip to the gas station, you shouldn't really see the fuel you're pumping that much. Unless you're pumping fuel directly into a canister or the pump is leaking, then it's more an experience of sounds than sights. In the case of diesel-powered vehicle, though, there are some notable differences in color that are important to understand.

What is diesel fuel supposed to look like? As it happens, the answer to that question actually depends entirely on what kind of vehicle you're driving, as well as which diesel pump you're using at the gas station. If you're just driving your own private diesel-powered vehicle, then the diesel fuel you pump should be clear and not have any particular color. However, if you check a canister of diesel fuel and see that it has a distinctive color, then that fuel has already been specially marked for certain vehicles. Unless you're a construction worker, farmer, or government employee, you probably shouldn't use it.

If you visit the diesel pump at your local gas station and pump some fuel into a clear, colorless canister, then the fuel you get should be equally colorless. Regular diesel fuel for consumer-grade vehicles has no distinct quirks or colorations — it's completely clear.

Clear diesel is standard diesel fuel, intended for use in ordinary on-road vehicles like pickup trucks, SUVs, and big rig trucks. Any and all diesel vehicles that are cleared for safe driving on a road or highway can and need to use this kind of diesel fuel. Not only is the clear diesel you get at a gas station properly formulated for traveling purposes, it's also subject to regular fuel taxes, which help to pay for things like highway maintenance.

Much like regular gasoline, clear diesel can be widely purchased at gas stations. If, however, you roll up to a diesel pump and are asked for a special fuel card, then you're in the wrong place.

While regular, clear diesel is used by civilians on the road, professional workers and government employees use a slightly different kind of fuel, collectively known as dyed diesel. Dyed diesel comes in two colors, red and blue, and while these fuels are functionally similar to the colorless kind, their usage is heavily regulated.

Red diesel fuel is only intended for use in heavy-duty machinery, generators, or off-road vehicles like tractors and bulldozers. This is why it's known as off-road diesel instead of regular diesel. While gas stations may have pumps available for this kind of fuel, you can only access them through the use of the aforementioned special fuel cards. Blue diesel, meanwhile, is only permitted for use in official government vehicles, such as military equipment. This kind of fuel is not publicly sold in any way.

Because dyed diesel fuel is used for official purposes, it typically isn't taxed, which makes it cheaper. If, however, a commercial vehicle is discovered on the road using any kind of dyed diesel, the driver could be subject to thousands of dollars in fines.

Incidentally, the color of your diesel fuel has nothing to do with the color of your engine exhaust. If your diesel truck is producing blue smoke, for example, that's because it's burning too much motor oil, not because of blue diesel.